Process for cracking petroleum oil



ODD-13, v1931. A. D. DAVID 1,827,073

ROCESS FOR CRACKING FETROLEUM OIL l Original Filed Feb. 7, 1925 Patented oa, 13, 1931 UNITED STATES PATENT ort-Ica AUDREY D. DAVID, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE UNIVERSAL OIL PROD- UCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS FOR GRACIIING PETROLEUM OIL Application led February 7, 1923, Serial No. 617,447. Renewed September 14, 1928.

This invention relates to improvements in a process for convertin petroleum hydrocarbons of a relatively hig molecular weight to those of a lower weight, the latter having the '5 characteristics of gasoline.

' Among the objects of. the invention are to provide a process in which the reflux condensate separated out during the dephlegmating of the vapors is cooled prior to rem' cycling, and its heat transferred to the raw oil to preheat the same; to provide a process in which the heat of the redux condensate is also utilized to redistill the pressure distillate which is recycled through the heating stage through which the hot reflux is circulated, and to provide an apparatus 'for carrying out .this process.

The single figure is a diagrammatic view of the plant, certain of the elements being reduced in scale and placed in a convenient position so as to more clearly bring out the details of |the piping.

Referring to the drawing, the raw oil to be treated is introduced from any convenient source such as the reservoir or tank 1, and is directed through the pipe 2 controlled by the valve 3 to a pressure pump 4 from which it is discharged through the line 5 controlled by the valve 6 through a coil 7 positioned in a chamber 8 through which the hot reflux is circulated as hereinafter explained. From the dischar e end of the coil, theA preheated oil passes tlxrough the pipe 9 regulated by the valve 10, and is conducted through the charging line 11 to the heating coils 12 positioned in the side tired furnace 13, which is preferably heated by means of gas burners, not shown. l

- The oil after circulating through the furnace is raised to a conversion temperature,

` and is directed through the transfer line 14 controlled by the valve 15 to the expansion chamber 16.

The expansion chamber is equipped with try-cocks 17 for ascertaining the liquid level, and residuum drawol lines 18 controlled by valves 19. The residuum lines are pos1 tioned at different heights on the chamber so as to facilitate the withdrawal of the unvaporized and residual substances, should the tioned compartment 29.

carbon accumulate and clog one of the .lower lines.

The vapors evolved in the chamber pass oi through the vapor pipe 20 regulated by the valve 21 to the dephlegmating or refluxing '55 column 22 where they are caused to pass in a circnitous travel due to the positioning of balile or perforated plates 23 in the column. During this dephlegmating or reluXing pe. riod the higher boiling point oil constituents 30 are separated from the vapors and collectin the bottom of the column while the still vaporized portion passes olf from the top of the column through the line 24. The reiuxed condensate separated out in the dephlegmatingstage,is drawn olf from the lower part of the column through the pipe 25 regulated by the valve 26, and is directed to the lower compartment 8in which is positioned the preheating coil 7. In this compartment fm heat is extracted from the reiux condensate by the passage of the cool charging stock through the coil 7 positioned in the compartment. From the bottom of this tank or compartment 8, the oil is withdrawn through the 15 line 27 controlled by the valve 28, and is directed to a separate lower division or parti- After being relieved of further heaty in this chamber, the reflux condensate is drawn ofl through the line 30 regulated by the valve 31, and is charged by the pump 32 back into the heat coils through the pipe 1l. The cooling of the reflux in this manner permits its being recharged into the system by positive means-@5 such as a pump shown at 32. It has been foundtllat it is very difficult to handle reflux due to its high temperature when taken directly from the reuxing stage and recycled, but by extracting or relieving the reflux of its heat in separate cooling stages, the temperature is reduced to an extent where it may be easily recycled.

Returning to the vapors which are withdrawn from thertop of the dephlegmator through the pipe 24, these vapors are dlrected to a chamber 33 in which is positioned a coil 34. This coil contains recycled pressure distillate as hereinafter explained, and relieves the vapors of their heat causing condensation lll 54, a battery ot stills may ont certain ot the relatively higher boiling point fractions.,

The duid oil constituents :trom the chamber 33 pass through the pipe 35 controlled by the valve 36 to a second chamber or compartment 37 in which is positioned a cooling coil 38. Water or cool oil may be circulated through this coil in order to subject the still vaporized constituents to a final condensing action. 'llhe distillate and gases pass from. this chamber through the pipe 39 to they distillate receiver 40 which is equipped With a pressure`s relief valve 4l, pressure gauge 4Q, liquid level gauge 48, and a dravvolie line 44 controlled by a valve 45, rlhe drawoii line communicates `with a pressure distillate storage tank 46.

rl`he distillate trom the storage tank may be Withdrawn through the line 4T controlled by the valve 48 and recycled by means ot the pump 49 and line 50 through the coils 51 positioned in the chamber 29, and the coil 34 positioned in the chamber 33. rlhis recirculation of the pressure distillate through r the chambers in which the redux condensate and heated oil vapors from the top ont the dephlegmator are circulated, serves -to increase the temperature ot the recycled distillate prior to its being introduced through the line 52 controlled by the valve 53 to the Still 54 lin this still the pressure distillate is redistilled under atmospheric pressure, and the vapors dephlegmated in the tower 55 and. passed through the line 56 controlled by the valve 5'? to the condenser 58 trom which it is drawn od through the line 59, when is in condition tor refining.

ln place oi the single still, as shown at be used to retreat the recycled pressure distillateu From. the drawing, it is obvious that the process is economical in operation, as the heat in the redux condensate is utilised to preheat the ravv oil, and in addition reheat the pressure distillate prior its losing redistilled.

.ilso, in place olf subjecting the vapors irninediately to a linal condensing action, a portion ot their heat is extracted by the recirculation of the pressure distillate through a stage in which the hot vapors are circulated0 The extraction ot the heat troni the redur condensate also permits a positive recirculation by means ot the pressure pump, and permits the raising ot the velocity of the oil the heating tubes, or an increase in pressure over that maintained the vaporiaing chamber hy controlling these diterential pressures by the valve lvleretoi'ore, vhere the velocity and pres- .sure of the recirculated tvas dependent upon the height ot the maintained hy height ont the dephle tor, the velocity li s s the means asesora tor positive recirculation, a more accurate control may be obtained.,

l claim as my invention:

A process of treating hydrocarbon oil consisting in continuously passing the oil through a heating zone wherein it is raised to a conversion temperature, in discharging the oil into an expansion zone wherein substantial vaporization occurs9 in passing the vapors issuing from said expansion zone to a dephlegmator, in condensing the dephlegmated vapors as pressure distillate in passing the hot reilux condensate from said dephlegmator to a zone of heat interchange through which the incoming raw oil is passed, in withdrawing the reiluxcondensate from said zone of heat interchange and in returning it under applied pressure to the heating zone for retreatment, in redistilling the pressure distillate and in utilizing the heat of the vapors issuing from the dephlegmator to preheat the presure distillate prior to such redistillation..

AUBREY l). Dilll). 

